1. Field of the Invention
The present invention relates generally to a data transfer control apparatus, a data transfer control system and a data transfer control method. More particularly, the invention relates to a data transfer system exchanging data between a plurality of circuit modules using data bus.
2. Description of the Related Art
For increasing data transfer amount in a data transfer system, speeding up and increasing of transfer bit number have been considered. Time division has also been practiced.
In the foregoing method of speeding up and increasing of transfer bit number, there are physical and electrical limits. On the other hand, considering transfer efficiency only by time division, during transferring of certain data, connection is established by point-to-point connection to lower transfer efficiency.
On the other hand, when all circuit modules are connected by point-to-point connection system, amount of wiring becomes huge. Therefore, if connection is established between only certain predetermined circuit modules, a problem is encountered in sacrificing of freedom. As set forth above, the conventional data transfer system employing data bus encounters a problem not adapted for large amount data transfer.
Therefore, the present invention has been worked out for solving the problem set forth above. It is an object of the present invention to provide a data transfer control apparatus, a data transfer control system and a data transfer control method, which can dynamically switch data transfer modes between respective circuit modules connected through data bus, between a time division and a space division multiplexing for enabling improvement of data transfer efficiency.
According to one aspect of the present invention, a data transfer control apparatus for controlling data transfer between a plurality of circuit modules through data bus comprises control means for controlling variation of a data transfer bit width of the data bus.
According to the second aspect of the present invention, a data transfer control system performing data transfer between a plurality of circuit modules through a data bus having a predetermined bit width, comprises bus bit width variation control means for controlling variation of data transfer bit width of the data bus.
According to the third aspect of the present invention, a data transfer system comprises:
a plurality of circuit modules;
a data bus having N bit width which is an integer greater than or equal to two for transferring data between the circuit modules;
interface means for performing transmission and reception of data between the circuit modules and the data us;
data transfer control means for performing control of transfer of the data bus between the circuit modules,
the data transfer control means including switching command means for commanding switching between a transfer de performing data transfer with the N bit width and a data transfer with a bit width of a quotient derived by dividing the integer N by at least one divisor which is other than one;
each of the interface means having switching means for switching control of data bit width of transmission and reception data of the circuit modules depending upon the transfer mode by the switching control means of the data transfer control means.
According to the fourth aspect of the present invention, a data transfer method controlling data transfer between a plurality of circuit modules through a data bus, comprises the step of controlling variation of a data transfer bit width of the data bus.
In the operation of the present invention, assuming he bit width of the data bus connecting a plurality of circuit modules is taken as 4n (n is natural number) bits, for example, the bit width is controlled to selectively switch between a transfer mode to use data bus as one data bus of 4n bit width, a transfer mode to use the data bus as two data bus of 2n bit width, and a transfer mode to use the data bus as four data bus of n bit width, to achieve the foregoing object.